Light bulb



FIG. 1 is a front perspective view of a light bulb illustrating my new design;

FIG. 2 is front elevation view thereof, the rear elevation view being identical;

FIG. 3 is a right side elevation view thereof, the left side elevation view being identical;

FIG. 4 is a top plan view thereof; and,

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a light bulb, as described and shown. 